<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        div{
            background-color: aqua;
        }
        .yans{
            background-color: blue;
        }
        div button{
            background-color: yellow;
        }
        button:hover{
            background-color: palegreen;
            cursor: pointer;
        }
        button:active{
            background-color: blueviolet;
        }
    </style>
</head>
<body>
    <div>212</div>
    <button>登录</button>
</body>
</html>